23.98 or 24fps Capture Rate for Sundance Submission

[Jamie A]

Hi all,

We're about to start shooting with our Dragon & will be submitting the short film to Sundance.

I assume it doesn't matter, but is there any difference in post if we shoot at 23.98 or 24fps?

Like I said, it's primarily for Sundance but we may have other deliverables - mainly online formats.

Thanks....

 

[Marc Wielage]

I generally tell my clients, shoot, edit, and mix the entire project at 23.98. At the very end, if you need a 24.00fps version for a DCP, it's one button to fix this. Otherwise, ask the distributor or festival what they want as a delivery format and follow those specs to the letter. Whether 23.98 or 24.00, it's not a problem at the very end. But 24.00fps capture, edit, mix, and color are very unusual choices in post for the projects I see.

 

[Joe D'Arcy]

I generally tell my clients, shoot, edit, and mix the entire project at 23.98. At the very end, if you need a 24.00fps version for a DCP, it's one button to fix this. Otherwise, ask the distributor or festival what they want as a delivery format and follow those specs to the letter. Whether 23.98 or 24.00, it's not a problem at the very end. But 24.00fps capture, edit, mix, and color are very unusual choices in post for the projects I see.

Hi Marc,
Is it a serious problem to convert from 25.00fps to 24.00fps in post for a DCP. What would you recommend?

 

[Gunleik Groven]

Hi Marc,
Is it a serious problem to convert from 25.00fps to 24.00fps in post for a DCP. What would you recommend?

It's often done by re-timing the video and re-tuning the audio. Pretty trivial if done that way.

 

[Kristin Stewart]

I wouldn't convert a 25 fps project to 24 fps for a DCP. I would stay at 25 fps, and do the DCP at this frame rate, we're doing hundreds of these and never had any issue of server playback.

As for the first question, I'm not American, but unless you've some broadcast delivery in mind, I would suggest to shoot at 24 fps : DCP's, web delivery, can be at 24 fps. Progressive Blu-Ray's can also be at 24 fps. Round numbers are always easier to manage in post ;-)

Kristin

 

[Joe D'Arcy]

Thanks Gunleik and Kristin

 

[Patrick Tresch]

Hi Marc,
Is it a serious problem to convert from 25.00fps to 24.00fps in post for a DCP. What would you recommend?

I shoot 25p and forget about 24p for DCP.

Pat

 

[Sergei Franklin]

Because of legacy issues when HD was introduced the US shoots everything at 23.98 and converts to 24 for the DCP.
Most of the world shoots at 24.

You can use Cinematools or EditReady to change framerate or use Davinci and output project as one clip.

 

[Patrick Tresch]

Because of legacy issues when HD was introduced the US shoots everything at 23.98 and converts to 24 for the DCP.
Most of the world shoots at 24.

This legacy is not due to HD introduction in the US but due to an "ingeneering error" in the introductin of color TV in the 50's. PAL contries used another way to do it and have since the beginning one format : 50hz 25p 50i.



In January 1950, the Committee was reconstituted to standardize color television. In December 1953, it unanimously approved what is now called the NTSC color television standard (later defined as RS-170a). The "compatible color" standard retained full backward compatibility with existing black-and-white television sets. Color information was added to the black-and-white image by introducing a color subcarrier of precisely 3.579545 MHz (nominally 3.58 MHz). The precise frequency was chosen so that horizontal line-rate modulation components of the chrominance signal would fall exactly in between the horizontal line-rate modulation components of the luminance signal, thereby enabling the chrominance signal to be filtered out of the luminance signal with minor degradation of the luminance signal. Due to limitations of frequency divider circuits at the time the color standard was promulgated, the color subcarrier frequency was constructed as composite frequency assembled from small integers, in this case 5×7×9/(8×11) MHz.[7] The horizontal line rate was reduced to approximately 15,734 lines per second (3.579545×2/455 MHz) from 15,750 lines per second, and the frame rate was reduced to approximately 29.970 frames per second (the horizontal line rate divided by 525 lines/frame) from 30 frames per second. These changes amounted to less than 0.1 percent and were readily tolerated by existing television receivers.[8][9]


You will shoot 8k but still be bugged by a decision made 65 years ago.

 

[Terry VerHaar]

This is an issue that pops up every once in awhile. It still befuddles me a bit. Whenever I look at it again, thinking that it is finally "safe" to go to 24 rather than 23.98, the thing that gets introduced (IIRC) is the issue of sound. Someone please correct me if I am wrong, but I seem to recall that shooting at 24 will end up screwing with sound synch; which tends to be recorded at 23.98 for some reason. I have seen it said that the simplest, and safest, thing to do is just stick with 23.98 unless, of course, you are actually shooting film.

One more time... ? :willy_nilly:

 

[Nick Fury]

This is an issue that pops up every once in awhile. It still befuddles me a bit. Whenever I look at it again, thinking that it is finally "safe" to go to 24 rather than 23.98, the thing that gets introduced (IIRC) is the issue of sound. Someone please correct me if I am wrong, but I seem to recall that shooting at 24 will end up screwing with sound synch; which tends to be recorded at 23.98 for some reason. I have seen it said that the simplest, and safest, thing to do is just stick with 23.98 unless, of course, you are actually shooting film.

One more time... ? :willy_nilly:

Hi terry!

This is most often the case, for U.S. based productions. With proper Tc clocks and synch, it makes the issue rather facile. As I posted on another thread, the new Ts-TCP Timecode Buddy and Denecke combo, if you don't have a slate and a Tc system is a strong consideration, although, you will have to get the Time code Buddy receivers everywhere that is required in the production-Teradek, Camera, SOund recorder, etc..

Another option is the Zaxcom, Zaxbet system, for sending Tc, with calibrated ERX's. Bear in mind, the ERX's can now be calibrated for Tc and you can also use the system for IFB. The other features that Zaxcom offer, WRT recording, etc., then make a compelling case.

BTW, the 23.98 WRT RED Dragon was an issue from some devices, including Zaxcom, for a bit, but now sorted and work a treat.

Thank you very much

Fury

 

[David Mullen ASC]

The sound can be recorded either way for 23.976 or 24 -- the issue is sound editing and mixing. In the old days, sound editors would get an NTSC tape copy of the offline edit and work from that, so all of the sound post in an NTSC country was done at 23.976, even for 24 fps film-shot productions, which was transferred to NTSC at 23.976 fps.

So even today when it is possible to share offline 24P Quicktime files with sound editors and avoid NTSC issues, most of the post industry in the U.S. is still geared towards 23.976 / 59.94i and of course, 60 Hz HD broadcast is still that way.

I did one of the first 24P HD features back in 2000 on the F900 -- and used straight 24P since I shot film at 24 fps -- and I remember asking the editor how the sound mix was going and she said "fine, except that I'm having to manually slip the sound sync on every reel because it's slightly drifting". That's when I realized that all of the sound post had been done at 23.976 because of NTSC offline cuts.

Anyway, since then, I've always shot digital at 23.976 and never had a problem.

 

[Terry VerHaar]

The sound can be recorded either way for 23.976 or 24 -- the issue is sound editing and mixing. In the old days, sound editors would get an NTSC tape copy of the offline edit and work from that, so all of the sound post in an NTSC country was done at 23.976, even for 24 fps film-shot productions, which was transferred to NTSC at 23.976 fps.

So even today when it is possible to share offline 24P Quicktime files with sound editors and avoid NTSC issues, most of the post industry in the U.S. is still geared towards 23.976 / 59.94i and of course, 60 Hz HD broadcast is still that way.

I did one of the first 24P HD features back in 2000 on the F900 -- and used straight 24P since I shot film at 24 fps -- and I remember asking the editor how the sound mix was going and she said "fine, except that I'm having to manually slip the sound sync on every reel because it's slightly drifting". That's when I realized that all of the sound post had been done at 23.976 because of NTSC offline cuts.

Anyway, since then, I've always shot digital at 23.976 and never had a problem.

Thanks, David. That very much states clearly what I thought I'd remembered hearing many time in the past. It's nice to hear it from someone who can be considered an "authority." Funny thing is, I guess what you are saying is that it's safe to shoot 23.976 because that's the way we've always done it and that's they way people expect it to be. I guess if the industry had one big "ah hah" moment, we could switch to 24 but until then...

23.976 it is! :001_smile:

 

[Marc Wielage]

Is it a serious problem to convert from 25.00fps to 24.00fps in post for a DCP. What would you recommend?

No problem at all -- it's one button. "Convert from 23.976 -> 24.00fps." Not a big deal. Moves everything up .1%.

 

[Craig Lees]

Hi Joe,

re: 25 to 24 conversion...

If you or someone you know has an old copy of FCP7, drag in your 25fps film & doubleclick it to load it- tools menu - conform 25 to 24 and voila! HOWEVER, duplicate your 25fps movie first before doing this & rename it @24 as this frame conversion does it at the root level & there is no going back. Going from 24 to 25 IS NOT SO EASY!!

Conform & pin the audio to 96 for cinema in Protools using a 24fps timebase QT proxy as a guide for lip-sync & bounce it as a 24bit 48khz .wav file.

You can even attach all these together into a DCP yourself for free using Open DCP if you export 24fps timebase TIFFs. Just make sure you have plenty of HDD space for those TIFFs, give yourself plenty of time to perform the JPEG2000 conversion and drag your final DCP onto a BIG .ntfs formatted USB stick (you can use the Paragon ntfs read & write plugin / 2 week free trial to do this on a Mac).

have fun!

Craig Lees
3dstories.co.uk
ED SX UK

 

[Joe Riggs]

I seem to recall that shooting at 24 will end up screwing with sound synch; which tends to be recorded at 23.98 for some reason

This is an area that confuses me as well but from what I understand, sound can work for 23.976 or 24 or 29.976, I don't think the sound recordist has to set the framerate on his recorder,
because I think sound doesn't have a frame rate. In essence if you shoot any of those frame rates, the sound mixer can record sound like they normally would and it should match up...I think?

I'd like a sound mixer to chime in to confirm or deny this...Marc Wielage?


However, when dealing with jam syncing timecode, that's a different story obviously that would need to be set to the shooting frame rate.

 

[Terry VerHaar]

This is an area that confuses me as well but from what I understand, sound can work for 23.976 or 24 or 29.976, I don't think the sound recorder has to press some special button.
In essence if you shoot any of those frame rates, the sound mixer can record sound like they normally would and it should match up...I think?

I'd like a sound mixer to chime in to confirm or deny this...Marc Wielage?


However, when dealing with jam syncing timecode, that's a different story obviously that would need to be set to the shooting frame rate.

I'd welcome further input s well, but my understanding is that the sound recordist CAN record at those different frame rates but usually doesn't by default. That's why I said above that it was really just a matter of "this is how we've always done it." So, "normal" recording wouldn't cut it with picture recorded at 24fps -at least for longer takes since drift would become noticeable. OTOH, coordinating with the sound recordist to record at 24 to match your picture, probably would. At least, that's how I understand it.

 

[Elsie N]

Hi Joe,

re: 25 to 24 conversion...

If you or someone you know has an old copy of FCP7, drag in your 25fps film & doubleclick it to load it- tools menu - conform 25 to 24 and voila! HOWEVER, duplicate your 25fps movie first before doing this & rename it @24 as this frame conversion does it at the root level & there is no going back. Going from 24 to 25 IS NOT SO EASY!!

Conform & pin the audio to 96 for cinema in Protools using a 24fps timebase QT proxy as a guide for lip-sync & bounce it as a 24bit 48khz .wav file.

You can even attach all these together into a DCP yourself for free using Open DCP if you export 24fps timebase TIFFs. Just make sure you have plenty of HDD space for those TIFFs, give yourself plenty of time to perform the JPEG2000 conversion and drag your final DCP onto a BIG .ntfs formatted USB stick (you can use the Paragon ntfs read & write plugin / 2 week free trial to do this on a Mac).

have fun!

Craig Lees
3dstories.co.uk
ED SX UK

Slight deviation from topic, but is there any problems in post caused by recording sound at 96khz over 48? Is there much of a reward for recording at 96?

 

[Joe Riggs]

Terry, you might be correct (but I wonder if this has to do with timecode). I realize the h4n is not a pro piece of gear but you don;t have to set a frame rate on that. However, I found this from the sound devices website about their pro gear but would like a working professional to give us the final word.

1. If you are about to shoot and you have been unable to get any information from pre-production, use the following suggestions to determine which sample rate / frame rate combination to use. These will provide post with the greatest flexibility. 48k / 25 If picture is to be shot at true 24 or 25 fps and is to be edited in a PAL video environment. 48k / 30 If picture is shot at true 24 fps and to be edited in an NTSC environment. 48k / 29.97NDF If picture is shot on video at 23.976 or 29.97 and to be edited in an NTSC environment.

The last line is particularly interesting as it is saying that 48k / 29.97NDF works with 23.976 or 29.97.

 

[MichaelP]

23.876 editing and 29.97 was the standard of working for many years when dailies were NTSC and sync timecode was 29.97 preferably NDF due to the consistent timecode to cadence relationship for picture. HD now allows 24fps timecode and it is now a matter of playback speed @ sample rate - so 23.976 @ 48kHz or 24.000fps at 48kHz. If posting at 23.976 record the former. If posting at 24.000 record the latter. For film that was shot at 24.000 and post was done at 23.976, then audio would be recorded at 48.048kHz so there would not be a sample rate conversion, but rather a sample for sample playback resulting as .1% slower.

As far as timecode goes, there really isn't one for audio, it really is sample from midnight based on sample rate. From there any timecode can be created. But for ease of workflow, have the speed set to match the picture rate.


Michael